The National Institute on Money in State Politics now provides a service where users can submit queries and download data in xml format. The documentation for the service (which requires setting up an account login) is here.
They also include services for generating various graphic reports including a Political Contribution Logorithmic Scatterplot Profile with interactive javascript inspection of candidates.
I did quick cut-and-paste from another site which uses thier data, and was able to generate network maps of the top tend funders for a few california candidates. But with access to the full DB via the API, it is possible to do much more sophisticated maps and even animations – for most states they have data going back several years.